Echolocation in sympatric Peale's dolphins (<i>Lagenorhynchus australis</i>) and Commerson's dolphins (<i>Cephalorhynchus commersonii</i>) producing narrow-band high-frequency clicks

Kyhn, Line A.; Jensen, Frants H.; Beedholm, Kristian; Tougaard, Jakob; Hansén, Michael; Madsen, Peter T.

doi:10.1242/jeb.042440

Cited by 94 publications

(126 citation statements)

References 32 publications

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“…commersonii and P. phocoena produce very similar sounds (Madsen et al, 2005a;Kyhn et al, 2010), perhaps indicating that the two species hear similar sounds, or share prey capture or predator avoidance strategies. This might confirm that shapes associated with PC 3 are subject to environmental selective pressures more so than Jaw Flare and Symphysis Elongation.…”

Section: Discussionmentioning

confidence: 99%

Shape analysis of odontocete mandibles: Functional and evolutionary implications

Barroso¹,

Cranford²,

Berta³

2012

Journal of Morphology

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Odontocete mandibles serve multiple functions, including feeding and hearing. One hypothesis is that sound enters the hearing apparatus via the pan bone of the posterior mandibles (Norris, 1968). Another viewpoint, based on computer models, suggests that sound enters primarily through the gular apparatus and the opening created by the absent medial wall of the posterior mandibles. The posterior region of each mandibular ramus has a large, hollow cavity called the mandibular foramen that contains a bulging mandibular fat body (MFB), which terminates on the bony tympanoperiotic complex. The acoustic properties of these fat bodies suggest that they refract sound. This unambiguous link between form and function has catalyzed this current study of mandibular shape. Previous studies have described odontocete mandibles using linear morphometrics and focused on multiple populations within single genera. Geometric Morphometrics (GM) is used to avoid some limitations of linear morphometric studies, using relative 3-D landmark positions instead of lengths. This technique measures shape only, excluding any scaling, rotational, and positional effects.The primary objective of this study is to use GM to quantify mandibular shape across all major lineages of Odontoceti. Eighty-five mandibles, comprised of 40 species, representing all major lineages were included in the shape analysis. Twelve landmarks found on each mandible represent regions of the symphysis and mandibular foramen. The majority of shape variation was found in Jaw Flare and Symphysis Elongation (85.5%). Shape differences in the mandibular foramen also accounts for a portion the total variation (10.9%). The mandibles are an integral component of the sound reception apparatus in toothed whales and the geometry of the mandibular foramen likely plays a role in hearing.The second objective of this study is to assess correlates of hearing and mandibular foramen geometry derived from the GM shape analysis, as well as from linear morphometrics. Echolocation peak frequency (EPF) was used as a measure of sound reception. Odontocete anatomy may emphasize frequencies they need to hear and suppress others in a returning echo during echolocation. Frequencies can be characterized by corresponding wavelengths. Surface area between the four landmarks that represent the mandibular foramen was calculated to assess the relationship between EPF and dimensions of a receiving structure (i.e. mandibular foramen and corresponding MFB). A significant relationship between size of the foramen and EPF was found, suggesting that size of the foramen may limit lower frequencies (longer wavelengths) from propagating through the mandibular fat body.

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Section: Discussionmentioning

confidence: 99%

Shape analysis of odontocete mandibles: Functional and evolutionary implications

Barroso¹,

Cranford²,

Berta³

2012

Journal of Morphology

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“…Recordings were analysed using customwritten scripts in Matlab 7.5 (MathWorks, Natick, MA, USA). To be accepted as an on-axis click, a click had to fulfil a set of criteria following Kyhn et al (2010): (1) it had to be part of a click series of at least five consecutive clicks with received levels exceeding the 154 dB re. 1 µPa ( peak) threshold and where received levels increased and then decreased within the click series.…”

Section: On-axis Click Criteriamentioning

confidence: 99%

“…For all on-axis clicks localised to less than 21 m, the received level at each of the seven hydrophones was back-calculated to estimate SL at 1 m and then normalised relative to the signal with highest back-calculated amplitude. Off-axis angles, together with normalised apparent SLs, were then used to estimate a composite vertical beam pattern through a single parametric fit in which piston diameters from 1 to 20 cm were tested in 0.01 cm increments (Kyhn et al, 2010). For each piston diameter tested, a goodness of fit was calculated as the sum of squared error between observed and predicted SLs.…”

Section: Beam Pattern Estimationmentioning

confidence: 99%

Amazon river dolphins (Inia geoffrensis) use a high-frequency short-range biosonar

Ladegaard

Jensen

Freitas

et al. 2015

Journal of Experimental Biology

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Toothed whales produce echolocation clicks with source parameters related to body size; however, it may be equally important to consider the influence of habitat, as suggested by studies on echolocating bats. A few toothed whale species have fully adapted to river systems, where sonar operation is likely to result in higher clutter and reverberation levels than those experienced by most toothed whales at sea because of the shallow water and dense vegetation. To test the hypothesis that habitat shapes the evolution of toothed whale biosonar parameters by promoting simpler auditory scenes to interpret in acoustically complex habitats, echolocation clicks of wild Amazon river dolphins were recorded using a vertical seven-hydrophone array. We identified 404 on-axis biosonar clicks having a mean SL pp of 190.3±6.1 dB re. 1 µPa, mean SL EFD of 132.1±6.0 dB re. 1 µPa 2 s, mean F c of 101.2±10.5 kHz, mean BW RMS of 29.3±4.3 kHz and mean ICI of 35.1±17.9 ms. Piston fit modelling resulted in an estimated half-power beamwidth of 10.2 deg (95% CI: 9.6-10.5 deg) and directivity index of 25.2 dB (95% CI: 24.9-25.7 dB). These results support the hypothesis that river-dwelling toothed whales operate their biosonars at lower amplitude and higher sampling rates than similar-sized marine species without sacrificing high directivity, in order to provide high update rates in acoustically complex habitats and simplify auditory scenes through reduced clutter and reverberation levels. We conclude that habitat, along with body size, is an important evolutionary driver of source parameters in toothed whale biosonars.

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“…Passive acoustic monitoring (PAM) techniques involve the detection of cetacean vocalizations from either towed or static hydrophones, and this method is increasingly being used to collect data on cetacean habitat use (e.g., Rayment et al, 2009b;Simon et al, 2010), behaviour (e.g., Leeney et al, 2007;Van Parijs et al, 2009;Akamatsu et al, 2010;Clausen et al, 2010;Kyhn et al, 2010), and even to estimate abundance (e.g., Marques et al, 2009;Whitehead, 2009). Static acoustic monitoring (SAM), using moored equipment to detect cetacean vocalizations from a fixed area, enables the observation of trends in relative abundance and of behaviours of target animals within a focal area (Kimura et al, 2010) and has several advantages over visual techniques.…”

Section: Introductionmentioning

confidence: 99%

“…The clicks of Heaviside's dolphins conform to the model of species using NBHF clicks (Morisaka & Connor, 2007). Heaviside's dolphin clicks were reported to have a mean centroid frequency of 125 kHz (range 118 to 132 kHz), click duration of 74 μs, inter-click intervals ranging from 2 to 113 ms (Morisaka et al, 2011), and overall characteristics similar to the clicks of other Cephalorhynchus species (Kamminga & Wiersma, 1982;Dawson & Thorpe, 1990;Kyhn et al, 2009Kyhn et al, , 2010Götz et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Using Static Acoustic Monitoring to Describe Echolocation Behaviour of Heaviside’s Dolphins (Cephalorhynchus heavisidii) in Namibia

Leeney¹,

Carslake²,

Elwen³

2011

Aquat Mamm

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Static acoustic monitoring is a cost-effective, low-effort means of gathering large datasets on echolocation click characteristics and habitat use by odontocetes. Heaviside's dolphins (Cephalorhynchus heavisidii) were monitored using an acoustic monitoring unit, the T-POD, in July 2008 at a site of known high abundance for this species in Walvis Bay, Namibia. The T-POD successfully detected clicks from Heaviside's dolphins, and these clicks were detected in the 120 to 140 kHz frequency range. A distinct diel pattern to the hourly mean inter-click interval was observed, with higher values during daylight hours than at night, suggesting that click trains are produced at faster rates at night time. There was no apparent diel pattern in the proportion of buzz trains produced, however. A diel pattern in click activity was observed, with many more detection-positive minutes per hour recorded between dusk and dawn, and vocalization activity dropping to low levels in the middle of the day. This corresponded with visual observations made on abundance of dolphins in the study area. These results suggest that Heaviside's dolphins use this site primarily during the night. Static acoustic monitoring proved to be an effective technique for monitoring patterns of habitat use by Heaviside's dolphins.

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Echolocation in sympatric Peale's dolphins (Lagenorhynchus australis) and Commerson's dolphins (Cephalorhynchus commersonii) producing narrow-band high-frequency clicks

Cited by 94 publications

References 32 publications

Shape analysis of odontocete mandibles: Functional and evolutionary implications

Shape analysis of odontocete mandibles: Functional and evolutionary implications

Amazon river dolphins (Inia geoffrensis) use a high-frequency short-range biosonar

Using Static Acoustic Monitoring to Describe Echolocation Behaviour of Heaviside’s Dolphins (Cephalorhynchus heavisidii) in Namibia

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